Things you should know about water heaters for caravans and motor homes

Washing your hands, washing dishes, or even showering – if you travel with a caravan, you appreciate when hot water is readily available. We all know that caravans differ considerably, but so do water heaters for caravans and motor homes. This guide gives you an overview.

Types of water heating

Appliances to heat water in caravans run on gas, electricity, diesel or a mixture of energy types. Some water heaters even use warmth from heaters to generate hot water. Depending on what type of vehicle you have and your personal water requirements, various Truma appliances may be of interest to you: Therme, Boiler or Combi heater.

Truma Therme installation overview
The Therme has a capacity of 5 litres and is integrated into the existing warm air system of the caravan to heat water.
Truma Boiler Gas installation overview
The Boiler gas and Boiler gas/electric have a capacity of 10 litres. They heat the water without a power supply or with an additional heating rod.
Truma Boiler Elektro installation overview
The Boiler electric has a capacity of 14 litres. It heats water just with electricity and keeps the water hot for a very long time.
Example for the warm air distribution in a motor caravan
The Combi is a heater and hot water system in one. It has a capacity of 10 litres.

Therme: efficient use of warmth from the heater

A Therme heats the water using the available warmth from a heater. A warm air duct runs through the appliance which transfers heat to the water. The benefit: when the heater is running, you are utilising the thermal energy twice. Especially during inter-seasonal periods you have hot water to wash your hands or do the dishes.

The Truma Therme is especially suitable as a caravan water heater. It holds five litres and weighs just two kilograms. It is important that the Therme is integrated in the existing caravan warm air system near the heater so that as little heat is lost as possible. When the heater is not running, an electric heating element heats the water.

Decision guidance

Pro

  • Use thermal energy from the heater to heat water
  • Additional electric heating element integrated
  • Short heating time in electric mode
  • Easy to install

Con

  • Suitable only for caravans
  • Relatively low capacity

Boiler: large capacity, fast heating

If you also want to shower in your caravan, you should perhaps consider a boiler as a water heater. With a capacity of 10 to 14 litres, it holds enough hot water for two people to shower one after the other. Boilers run on gas, electricity, or a mixture of gas and electricity, making them suitable for caravans and motor homes.

Thanks to modern technology, they are so compact that they require very little installation space. For example, with the Boiler gas, you don’t need mains current. A powerful gas burner heats the water in about half an hour. If you want hot water faster than this, you need a boiler with an additional electric heating element. This reduces the heating time to about 15 minutes.

Woman taking a shower in a caravan

An electric boiler heats water using just electricity – and it keeps the water hot for a long time. The electric Truma Boiler is so well insulated using special foam made from expanded polypropylene (EPP), that the temperature falls by just one degree per hour.

Decision guidance

Pro

  • Large capacity, sufficient water for showering
  • Different modes of operation possible (gas, electric, mixed mode)
  • Fast heating, little heat loss

Con

  • Electric boiler completely reliant on mains current

Combination appliances: heating and hot water in one

A combination heater is a good alternative to a boiler, allowing you to heat water and your vehicle with just one appliance. Both functions can also be used separately. Truma Combi heaters are suitable for both caravans and motor homes and have a water container with a capacity of ten litres.

Combination appliances usually run on gas, which means that they don’t need a power supply. Some models have integrated electric heating elements that allow both water and the vehicle to be heated when the motor home is stationary at a campsite. Mixed gas and electric mode is then also possible. The diesel variants of the Combi heater are suitable only for motor homes, as they use diesel fuel from the vehicle’s tank.

Father and his son inside a caravan using the digital control panel CP plus
Decision guidance

Pro

  • Heating and hot water from just one appliance
  • Space-saving, as just one appliance is installed
  • Ten litre water capacity is sufficient for showering
  • Many different models for different needs

Con

  • Heater and water heater cannot be replaced individually

Tips: Cleaning water heaters

For hygienic reasons it is advisable to clean Therme, Boiler and Combi heaters regularly, especially after they have not been used for some time. Normal household vinegar essence or citric acid are suitable for decalcifying. Always pay attention to the manufacturer’s recommended mixing ratio on the package. Specialist camping shops also have special products to clean the complete fresh water system.

For more detailed information see the operating instructions!

Maintenance Truma Therme

The device must be descaled on a regular basis – at least twice a year. We recommend using suitable commercially available products to clean, sterilise and maintain the Therme. Products containing chlorine are not suitable.

If the heating-up time in 230 V mode is extremely long, the heating rod may be calcified. In this case, you should also decalcify the water system.

Maintenance Boiler Gas / Boiler Gas/Elektro

We recommend the use of suitable commercially available products to clean, sterilise and maintain the boiler. Products containing chlorine are not suitable.

The boiler should be heated to 70 °C at regular intervals to prevent infestation by microorganisms.

Clean the device and the ventilation slots with a dry, lint-free cloth.

Maintenance Electric boiler

We recommend the use of suitable commercially available products to clean, sterilise and maintain the boiler. Products containing chlorine are not suitable.

The boiler should be heated to 70 °C at regular intervals to prevent infestation by microorganisms.

Maintenance Combi heater

Clean the compartment where the unit is installed at least once annually.

  • Have an expert check the unit for dirt and clean it if necessary.
  • The safety/drain valve must be operated regularly (at least twice annually) to remove limescale deposits and to be certain that it is not blocked.

We recommend the use of suitable commercially available products to clean, sterilise and maintain the boiler. Products containing chlorine are not suitable.

The effectiveness of the use of chemicals to combat microorganisms in the appliance can be increased by heating the water in the boiler to 70 °C at regular intervals.

Combi E only

  • Select "Gas mode".
  • Set the water temperature to 60 °C.
  • Switch on the appliance.

Once the water in the boiler has reached a temperature of 60 °C, the burner will switch off. The appliance must stay switched on for at least 30 minutes and no hot water may be removed. The residual heat in the heat exchanger will heat the water up to 70 °C.

Tips: How to protect your water heater from frost

Completely drain your Therme, Boiler or Combi heater if you’re not planning on using your caravan or motor home in winter. If water remains in the water heater and freezes, the water container can burst. Therefore, observe these tips.

Draining the Therme

If the mobile home is not used during periods of frost, it is essential that the Therme be emptied.

  1. Interrupt current for water pump (main switch or trans former).
  2. Drain water from tank (or remove water pump from tank).
  3. Open taps in kitchen and (or) bathroom and set pre-mixing valve(s) – if available – to hot.
  4. Turn draining and ventilating valves (4) to full extent to open. 5. Check whether all the wa ter content (5 litres) has completely run out.

Never operate the Therme electrically without water contents! Don’t forget to turn the appliance off when the caravan is not being used! Drain in event of frost!

Winterization: Draining Truma Therme
Draining the boiler gas and gas/electric boiler

If the caravan is not being used during the frosty period, the Truma Boiler must be drained!

  1. Switch off the power for the water pump (main switch or pump switch).
  2. Turn on the hot water taps in the bathroom and kitchen.
  3. Open drain valve: lever vertical, position (f).
  4. The boiler will now be drained directly to the outside via the drain valve. Check that all the water has drained out of the boiler (10 litres)

Even if the cold water system is being operated without the boiler, the boiler will still fill with water. To avoid frost damage, the water in the boiler must be drained by operating the drain valve, even if the boiler has not been used. Alternatively, two hot water-resistant shut-off valves can be fitted upstream of the cold and hot water connection.

Never operate the boiler when it is empty.

Winterization: Draining Truma Boiler electro
Draining the electric boiler

If the caravan is not being used during the frost period, the boiler must be drained!

  1. Disconnect power to pump assembly (main switch or pump switch).
  2. Turn on the hot water taps in the bathroom and kitchen.
  3. Open safety/drain valve: Lever vertical, position (b).
  4. The boiler will now be drained directly to the outside via the safety/drain valve. Check that all the water has drained out of the boiler (14 litres).

If only the cold water system is being operated without the boiler, the boiler also fills up with water. To avoid frost damage, the water in the boiler must be drained by operating the safety/drain valve, even if the boiler has not been used. Alternatively, two hot water-resistant shut-off valves can be fitted upstream of the cold and hot water connection.

Winterization: Draining Truma Boiler electro
Draining the Combi heater

The boiler must be drained if the motor home / caravan is not being used during the frosty period.

  1. Switch off the power to the pump assembly (main switch or pump switch).
  2. Open hot water taps in kitchen and bathroom. In order to check the water that is flowing out, place an appropriate container (capacity 10 litres) beneath the drainage socket (d) of the drain valve.
  3. Open drain valve: Move lever to position (c) – vertical.
  4. The water from the hot water system drains through the drainage socket (d). The drainage socket (d) of the drain valve must be free of blockages (slush, ice, leaves, etc.) at all times so the water can drain easily!
  5. Check whether all of the water in the hot water system (10 litres) has been drained into the container via the drain valve.

Combi: The interior can be heated either with or without water, depending on the setting.
Combi E: The interior can be heated in gas, electrical or mixed mode, either with or without water, depending on the setting.

Winterization: Draining Truma Combi heater

Truma water heaters at a glance

Product Area of use Energy sources Volume Heating element Heating time
Therme Icon caravan Heater warmth
Electricity
5 L 300 W approx. 15 °C to approx. 60 °C: approx. 50 min. (electric mode)
Boiler gas Icon camper and caravan Gas 10 L approx. 15 °C to approx. 70 °C: approx. 31 min.
Boiler gas/electric Icon camper and caravan Gas/electricity 10 L 850 W / 1300 W approx. 15 °C to approx. 70 °C:
approx. 16 min. (mixed mode)
approx. 29 min. (electric mode)
approx. 31 min. (gas mode)
Boiler electric Icon camper and caravan Electricity 14 L 850 W approx. 15 °C to approx. 70 °C:
approx. 70 min.
Combi 4 Icon camper and caravan Gas 10 L approx. 15 °C to approx. 60 °C:
approx. 20 min. (water container only)
Combi 6 Icon camper and caravan Gas 10 L approx. 15 °C to approx. 60 °C:
approx. 20 min. (water container only)
Combi D 6 Icon camper Diesel 10 L approx. 15 °C to approx. 60 °C:
approx. 20 min. (water container only)
Combi 4 E Icon camper and caravan Gas/electricity 10 L 900 W / 1800 W approx. 15 °C to approx. 60 °C:
approx. 20 min. (water container only)
Combi 6 E Icon camper and caravan Gas/electricity 10 L 900 W / 1800 W approx. 15 °C to approx. 60 °C:
approx. 20 min. (water container only)
Combi D 6 E Icon camper   10 L approx. 15 °C to approx. 60 °C:
approx. 20 min. (water container only)
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If you require information about Truma Service Centres in the UK, please contact Truma UK on:

Contact
Phone: 01283 587960
E-mail: technical@trumauk.com

Service times
Monday – Friday 8.30 a.m. – 5.30 p.m.
Weekends and bank holidays: Closed

If you have a question about an appliance, always have information about the appliance type, year of manufacture and factory number at hand. You'll find this on the type plate on the appliance.

Truma type plate

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